International Journal of Electrical and Computer Engineering (IJECE) Vol. 12, No. 5, October 2022, pp. 4765~4771 ISSN: 2088-8708, DOI: 10.11591/ijece.v12i5.pp4765-4771  4765 Journal homepage: http://ijece.iaescore.com Application of green-emitting ZnS:Eu 2+ for boosting the spectrum of white light-emitting diode packages Dieu An Nguyen Thi 1 , Phuc Dang Huu 2 1 Faculty of Electrical Engineering Technology, Industrial University of Ho Chi Minh City, Ho Chi Minh City, Vietnam 2 Institute of Applied Technology, Thu Dau Mot University, Thu Dau Mot city, Vietnam Article Info ABSTRACT Article history: Received Aug 5, 2021 Revised Apr 16, 2022 Accepted May 11, 2022 Through utilizing a nonlinear application to acquire the best lumen efficiency (LE) for radiation (also known as LER) when color rendering index (CRI) value, especially CRI of R9 for strong red exceeds 90 with correlated color temperature (CCT) range of 2700-6500 K, the white light emitting diodes (WLED) package with adjustable CCT value and comprised of mixed-type light-emitting diodes (LEDs) can be acquired. The WLED model here contains blue and red LEDs with direct emission and a phosphor- conversion blue LED or pc/B-LED (including orange and green phosphors mixed with blue LED colorant). The peak wavelengths of each LED constituent are 465 and 628 nm for LEDs in blue and red, 452 nm for the blue LED colorant, 530 and 586 nm for the phosphors exhibiting green and orange colors. Under the CCT of 2722-6464 K, the attained actual LED package, either with conversion phosphor, in red or in blue, possibly displays both CRI and R9 values measured from 90 to 96, color quality scale (CQS) values measured from 89 to 94, with LERs and LEs of 303-358 lm/W and 105-119 lm/W, respectively. Keywords: Color homogeneity Color rendering index Luminous flux Monte Carlo theory White light emitting diodes This is an open access article under the CC BY-SA license. Corresponding Author: Phuc Dang Huu Institute of Applied Technology, Thu Dau Mot University No 6, Tran Van On Street, Thu Dau Mot city, Binh Duong province, Vietnam Email: danghuuphuc@tdmu.edu.vn 1. INTRODUCTION According to certain researches, a novel form of retinal cells that can assess illumination and the ganglion cells can interact with biological clock in our brain through signals [1], [2]. It was demonstrated that under unsuitable illuminated environments, the inner workings of mammals’ bodies can be disrupted and create detrimental results in their well-being, such as cancer [3]. As such, utilizing adjustable chromatic temperature in illuminations could improve our physical condition. In addition, this could diminish the need for medicines intended for alleviating sleep deprivation. As such, illuminations that imitate the significant chromatic temperature found in the noon sun, as well as the small chromatic temperatures found in the morning time and nighttime, can be a suitable choice, as our bodies have long become accustomed to these biological illuminations. There is another option that involves controlling said biological clock. When the biological illuminations can alleviate the tiredness of the people in traffic, it could lead to fewer fatal vehicular incidents [4]. There are certain difficulties in creating the white light emitting diodes (WLED) packages that possess adjustable correlated color temperature (CCT) values, which require us to simultaneously obtain outstanding color rendering index (CRI) output [5] under various CCT levels and produce the best lumen efficiency (LE) values. Researches have examined certain WLED packages mentioned above [6]–[10]. Researches proved that the NW/R/B package containing red and blue light-emitting diodes (LEDs) (with